SAX and DOM preference

Based on what learned from my readings on web and forums, I'll go for DOM with DOMDocument.

"SAX is better for memory efficiency but a bit complex and chalenging."
"DOM is uses loads whole xml into memory but easier and widely prefered and used."

The question is, based on your experiences, what should be the max size of the xml file that I'll use or max lines? Since whole file will be loaded into memory and my site is being hosted on one of those online hosting companies.